Air pressure actuated switch for controlling the operation of a motor



Feb. 11, 1969 H. F. HOPE 3,427,417

AIR PRESSURE ACTUA'TED SWITCH FOR CONTROLLING THE OPERATION OF A MOTOR Filed June 15, 1966 INVENTOR HENRY F HOPE United States Patent 2 Claims ABSTRACT OF THE DISCLOSURE An air pressure actuated switch for energizing a motor when the air pressure is high and vice versa. The air pressure is constant at the source but its impact on the switch is varied by the presence and absence of an obstruction between the source and the switch.

This invention relates to a control apparatus for intermittingly activating or de-activating a motor or othe source of energy.

More particularly, this invention relates to means whereby the motor is activated and de-activated by an air pressure responsive control apparatus, the change in pressure being effected by the movement of a workpiece over a predetermined point.

One object of this invention is to provide an improved control apparatus of the type set forth.

A further object is to produce a control apparatus which is simple, foolproof, durable and inexpensive.

A still further object is to produce a control apparatus which is especially adaptable for use under conditions which do not permit the use of mechanical devices or the use of devices embodying light or heat.

A still further object is to provide an improved control apparatus which activates or de-activates a motor for intermittingly propelling X-ray negatives or other sheets from one location to another.

The full nature of the invention will be understood from the following specification and the accompanying drawings in which:

FIG. 1 is a side elevated view of a control apparatus embodying the invention and shows the apparatus ready to receive a workpiece to be propelled.

FIG. 2 is similar to FIG. 1 and shows the apparatus in the process of propelling an X-ray film from one location to another.

FIG. 3 is a view looking in the direction of line 3-3 on FIG. 2.

The invention includes a blower housing within which blades, not shown, are activated by a motor, also not shown, to cause a stream of air to flow from said housing through a substantially U-shaped conduit 12 and into chamber 14. One wall of chamber 14 is adapted to receive a diaphragm 16 which carries a rigid tip 18 for purposes hereinafter explained. The diaphragm may be constructed of rubber or of any other suitable material. The limbs 20 and 21 of the U-shaped conduit 12 are separated from the bight portion 24 thereof to provide passages 22 and 23 through which a film 24A, travelling on or above platform 25 may pass. Above the film is a cover 26. a

Adjacent chamber 14 is mounted a microswitch 2-8 which includes a movable activating arm 30, the free end of which is disposed in close proximity to tip 18 of dia- 3,427,417 Patented Feb. 11, 1969 ice phragm 16. Switch 28 is operatively connected to a motor, not shown, which actuates a film-feeding mechanism, not shown. Since theifilm-feeding mechanism forms no part of the invention, it is not shown, nor described. It is sufiicient to say that when the motor is energized, a film is propelled through passage 22 or passage 23, or both, that is, across the open ends of limbs 20 and 21 and the adjacent ends of bight portion 24. The feeding mechanism includes nip rolls 32 and 34which propel a film, or the like, toward the viewer in FIG. 1, or to the left as viewed in FIG. 3. Also, film guides 29 and 31 are provided to receive and support the film as it emerges from the nip rolls and to guide it to the next step or process.

The operation is as follows:

When no workpiece is being propelled between nip rolls 31 and 32, the air will fiow in the direction indicated by arrows 34 in FIG. 1. Because passages 23 and 22 are only wide enough to allow a film to pass through, not much air pressure is lost, so that the residual pressure of the air reaching chamber 14 will suffice to force diaphragm 16 outwardly, thereby causing tip 18 to move switch arm 30 to switch-closing position. This takes place as long as passages 22 and 23 are unobstructed. When a film obstructs the upper ends of limbs 20 and 21, the air pressure in chamber 14 falls and tip 18 is disengaged from switch arm 30 to open the switch and stop the filmfeeding mechanism. It will be understood that a film already engaged by the independently and constantly rotating nip rolls, will continue to move until it clears the upper ends of limbs 20 and 21.

The arrangement is such that a large standard film will obstruct the upper ends of both limbs, and that two small films can be moved simultaneously, with each of the films obstructing the upper end of one of the limbs.

What I claim is:

1. Apparatus for controlling the operation of a filmfeeding mechanism, said apparatus including:

an air chamber,

a generally U-shaped conduit having a bight portion and limbs, said limbs being severed from said bight portion with the respective severed ends juxtaposed to provide a passage therebetween,

the other end of one of said limbs being connected to a source of air under pressure,

the other end of the other limb leading to said chamber to transmit air under pressure of a pre-determined value from said source to said chamber,

a switch having a switch arm disposed near a wall of said chamber and movable to switch-closing position,

a diaphragm carried by said wall and movable, when the pressure in said chamber is at a pre-determined value, to a position in which it engages and moves said switch arm to switch-closing position, said diaphragm being automatically movable, in the opposite direction to open said switch when the air pres sure in said chamber is less than said-predetermined value.

2. Apparatus for intermittently activating a film feeding mechanism, said apparatus including:

a first conduit having spaced open ends,

a second conduit connected at one end thereof to a source of air under a pressure greater than the atmospheric pressure, and having its other end juxtaposed to one of said open ends and co-acting therewith to form a first film passage therebetween,

4 a third conduit connected at one end thereof to an aira 4 References Cited receiving chamber and having its other end juxtaposed to the other of said open ends and co-acting UNITED STATES PATENTS therewith to form a second film passage therebetween, 1 0 5 57 1913 Amet whereby some of the air flowing through said second conduit will flow through said first conduit and 5 F REIGN PATENTS through said third conduit into said air receiving 1,084812 7/1960 Germany chamber as long as neither of said openings is obstructed by a film passing through either of said passages, and

10 a r y blased swltch, H. BURKS, Assistant Examiner. a switch arm, and means carried by a wall of said air receiving air cham- US her and operative, in response to pressure within said ZOO-61.13

air receiving chamber to open said switch.

ROBERT K. SCI-IAEFER, Primary Examiner. 

